Contents
- 1Introduction
- 1.1Packaging and accessories
- 2Connectors & cabling
- 2.1Casing & cooling
- 3Input filtering
- 4Primary side
- 4.1+5 V stand-by rail
- 5Secondary side
- 5.1Build quality
- 6Load testing
- 6.1Loading +5 V SB
- 6.2Voltage hold-up time
- 6.3Combined loading
- 6.4Combined loading ripple
- 6.5Crossloading, overloading
- 6.6Crossloading, overloading ripple
- 6.7Fan speed and temperatures
- 7Conclusion and evaluation
- 7.1Thanks
- 7.2Discussion
Primary side
The primary side of the Corsair RM550x starts with a bridge rectifier, the GBU1506. It can handle continuous current of 15 A with heatsink at 100 °C and 600 V, or 200 A surge (8.3 ms) at 25 °C. Voltage drop is 1.1 V per diode at 7.5 A. It has small black aluminium heatsink mounted to itself. A single N-FET is used as the PFC switcher; it is either the Vishay SiHG30N60E (29/65 A at 150 °C and 600 V, Rds(On) 0.125 Ω at 15 A) in TO-247 package, or some Chinese copy. In such case it may even be an IGBT as they already start at these currents with similar markings. It bears style similar to older/industry Fairchild transistors but with some unknown logo so who knows. The diode is Cree C3D4060A (4 A at 155 °C and 600 V or 160 A surge (10 μs) at 110 °C, voltage drop of 2.4 V at 4 A and 175 °C) in TO-220-2 package. Both these devices are mounted on separate heatsink with no fins. The PFC coil seems big enough and is double-insulated using extra PCB beneath and insulation tape around.
Capacitor charged by the PFC circuitry is Nippon Chemi-Con KMQ 470 μF/400 V with endurance of 2000 hours at 105 °C (and ripple). Measures about 430 μF. CWT opted for the Infineon ICE3PCS01G PFC controller, for the primary switching there is ICE2SH01G resonant controller. There is also our favorite Champion Micro CM03X IC to lower “phantom load” and other losses. All three are located on a daughterboard which is between the PFC coil and switching transistors’ heatsink; its backside is also EMI-shielded with copper foil (not grounded).
The switchers themselves are two Infineon IPA50R280CE (7.5/42.9 A at 500 V and 25 °C, Rds(On) 0.28 Ω at 4.2 A and 25 °C, 0.66 Ω at 150 °C) in TO-220FP package. Their heatsink has no fins once again but notice how all the heatsinks and daughterboards channel the air into pre-determined corridors. The main switching transformer bears a Corsair logo and uses 35mm core.
+5 V stand-by rail
The stand-by rail is being controlled by On-Bright OB5269CP flyback PWM microcontroller, which is powered directly from the input filtering section. It controlls Ubiq Semiconductor QM03N65D MOSFET (3/6 A at 650 V and 25 °C, Rds(On) 4 Ω a1.5 A) in TO-252 SMD package (it is on the solder side of the board). Chemi-Con KY 47/25 capacitors are used for feedback and other circuitry around the stand-by rail.
Corsair-labeled transformer with 20mm wide core is used for transformation and PFC Device Corporation PFR20V45CT (20/250 A at 45 V and 25 °C, drop of 0.47 V per diode at 10 A and 25 °C) rectifier for single-wave rectification. Chemi-Con caps are used again for the filtration, this time KZE 2200/16 and KY 1000/10. So far so good.
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